Please post WIP images. I love grass fields!
Ha. Sure. Here's the latest.
You can see the lighting is still busted(haven't had time to really dig into it yet), but there are many more blades of grass. I had based most my work so far on the white paper that Lee did, but I've slowly started to drift away from some of the elements he uses. For example he populates his world with a vertex per grass blade (which means he needs N verts for N blades of grass). Right now I have 1 vert per heightmap cell and I use geometry shader instancing to populate that cell with 1 - 32 blades of grass. The attached picture is a 3x3 grid of grass blades, so 9 GS instances, per cell (with some small position offset randomization within the cell).
My hope is that massive parallel pipelines on today's cards can happily chew through the added work in the GS instance, so far it seems to be working. The framerate in the image is running in debug build, with no LOD on the grass (I have it setup, just not turned on yet), no visibility culling (beyond what the HW provides), and using a completely unoptimized shader. Turning the image to max instances(i.e. 32 blades of grass per cell) drops the FPS to 30 - 40s (which isn't bad and I suspect is more a fill rate issue than the actual number of verts but that's just a wild guess).
I'm sure I'll come across some massive flaw in my current approach, but for now it's working pretty well.